DISCUSSION: On the week of December 8, a trough moved over parts of North Dakota and Minnesota. The trough brought with it a dose of a very dry cold polar air from Canada into the U.S. leading to the first widespread below 0 degrees Fahrenheit temperatures across much of the Northern Plains of the 2019-20 Winter season. The trough also brought with it a strong wind which made the wind chill much more dangerously cold. However, some locations had below 0 temperatures in November but they were not as widespread. The wind was strong due to a tight pressure gradient in the upper atmosphere. A pressure gradient is a quantity that describes the change of pressure over a distance and is used to help determine wind speed at high levels of the atmosphere.
Wind chill is an apparent temperature developed to give a sense of how the temperature feels with how windy it is. It is used to help determine how long one should be outside before developing hypothermia and frostbite. However, wind chill is not always accurate as it does not factor in moisture especially if a person’s skin is wet or how many layers a person is wearing. In addition, wind chill is not consistent due to the minute time often varied in wind speed.
The trough slowly moved out before another one moved in with a warm front bringing warmer temperatures and snow to the area including up to an inch at Minneapolis-St. Paul International Airport. In a normal year, places like Minneapolis-St. Paul and St. Cloud, Minnesota are not below 0 degrees until late December or early January as winter progresses. The coldest areas are usually the rural counties in North Dakota and Minnesota with International Falls, Minnesota being the most consistently, coldest metropolitan area during the winter.
To learn more about other high-impact weather events occurring across North America, be sure to click here!
©2019 Meteorologist JP Kalb
Windy Conditions Across the Land of Enchantment! Photo Credit: (NWS, tropicaltidbits, Nations Online Project)
A typical setup for strong westerly winds will develop across much of New Mexico (otherwise known as the Land of Enchantment) particularly for this Sunday. Strong westerly flow aloft is currently anchored over much of the Desert Southwest into portions of the central Rocky Mountains. This typically generates a lee side surface cyclone. Depending on how deep the surface cyclone is, breezy conditions can develop. Sunday will be particularly susceptible to windy conditions as an upper level trough swings through the Desert Southwest region and into northern NM. This shortwave will intensify the surface low pressure and increase the winds above the surface. During the daytime hours, when surface heating begins and the boundary layer becomes well mixed, these stronger winds from aloft will mix down to the surface resulting in the aforementioned windy conditions on Sunday.
Image above: 500mb heights from the GFS model. Circled in black is the trough that will enhance windy condition on Sunday.
There are locations in southern New Mexico that are more susceptible to stronger winds in this type of setup. These include mountain ranges and more specifically on the eastern slopes of these mountain ranges.
Image: Map showing terrain features across New Mexico. Notice the Black Range and Sacramento Mountains labeled. These are typical high wind locations in southern NM, in addition to locations around the San Andres Mountains as well.
The Black Range and Sacramento Mountains in southern NM average about 8-9K feet in elevation with some peaks reaching around 10K ft. With a strong westerly wind, the mountains are higher in elevation and therefore will have higher winds. The east slopes of these mountains are susceptible to down-slope winds further enhancing these wind speeds. As a result, the NWS in Santa Teresa/El Paso and Albuquerque have issued a high-end wind advisory for these mountain ranges, the east slopes, and surrounding terrain. In addition, there is a lower end (meaning lower wind values) wind advisory for the rest of southern NM.
To learn more about impactful wind events across North America, click here!
©2019 Meteorologist Joe DeLizio